Bash

If your ~/.bash_profile is setup to not load aliases when running non-interactively (most likely the case), you need to explicitely load the aliases in your dmenu_run script: source ~/.bash_aliases

The above is sufficient to run aliases, but only if you type in the full name by hand — at this point, aliases aren't included in the list of known commands. To fix that, replace dmenu_path with compgen -c.